Traffic was heavy as a mix of cars, motorcycles, trucks and buses started streaming across the bridge. Vehicles moved slowly at first, but then picked up speed.
Many vehicles honked their horns as they drove across and a few motorists waved American flags.
The old bridge collapsed on August 1, 2007, killing 13 people and injuring 145.
The new bridge has 323 sensors that will generate an extensive record of how it handles the stresses and strains of traffic and Minnesota's harsh climate.